I've discovered an easy solution to a problem which plagues many of us. I have a 1936 Ford Pickup in for service. It jumped out of second really easily, so I pulled the transmission and rebuilt it. I used a better synchro but all original gears. I rebuilt the tower with new spring and plungers. After putting it all together again it was much better but I could still force it to jump out of gear at higher speeds and coming off the gas completely. This tech is for 1932-38 Ford 3-speed transmissions with single indent towers. So I pulled the tower and removed the 2/3 fork and selector shaft. I then carefully ground the second gear indent on the fork shaft about 1mm deeper and a bit wider so the plunger fitted in perfectly about 1mm deeper. Regularly checking the plunger for perfect fit. This also eliminated the tiny exit ramp which had been created over time. After I reassembled everything, I noticed that the second gear selection was a lot more positive and required more effort to return to neutral. A test drive followed and it remained in second on the overrun. This is a pretty easy 1 to 2 hour job which you can try. Easy because the transmission stays in the car. Budget 1 hour for the entire job, and 1 hour to replace the pin in the 2/3 fork. Sent from my SM-G935F using The H.A.M.B. mobile app
FWIW, Had a ‘36 box that used to pop out of 2nd. Then it wouldn’t even go into 2nd. Played around with the indent etc, still no better. Pulled it out, everything looked good, until I found what I believe was a broken thrust washer. Put a ‘39 box in it. - Good now.
Great tech @edwardlloyd always good to get input that worked and has been backed up with finished results. Cliff Ramsdell
No I didn't. But I tried to describe the process best I could. Sent from my SM-G935F using The H.A.M.B. mobile app
Overhauled a 1939 3spdwith 2 shift rails,still occasionally jumped out of 2nd when deaccelerating. Replaced the 2nd- 3rd detent plunger spring with the stiffest spring I could find. That cured it 100%. You could hardly feel any more effort needed to shift. Greg
There are many causes for that transmission to pop out of second. One of the things to fix is the detent as you say. I think you described that well. I made a small wooden jig so I could grind the groove on my drill press straight and square. The heavier spring is also helpful. My only caution here is.....be careful you don't grind too far or you will not be able to move the gear selector out of second gear. Your suggestion of 1/32" is a good guide.
The old fashion racer way is to put a hook on the dash and put the shifter around it to hold it in second and give it hell...